C语言解析RS232串口协议示例

/** ****************************************************************************** * @file cmd.c * @author * @version * @date * @brief 封装的用于通讯具体处理的函数命令。 ****************************************************************************** * @note * @copy * */ enum CMDTYPE {CMDTYPE_SETTING, CMDTYPE_POLLING, CMDTYPE_SAVING, CMDTYPE_CHANGING, CMDTYPE_ERROR}; //inputcmdlength是实际经过rs232传输的命令字节的个数, 从命令开始到结束符'\r'结束, 长度包含结束符在内 uint8_t Cmd_CheckRS232Cmd(char * inputcmdstr, uint8_t inputcmdstrlength) { char modulestr[MaxComStrLength] = "\0"; char paramstr[MaxComStrLength] = "\0"; char valuestr[MaxComStrLength] = "\0"; uint8_t addr = 0; uint8_t syntaxlevel = 0; enum CMDTYPE cmdtype = ProtocolAnalysis(inputcmdstr, inputcmdstrlength, modulestr, paramstr, valuestr, &addr, &syntaxlevel); if(cmdtype == CMDTYPE_SETTING) //设置 { //这里写入自己的处理程序 } else if(cmdtype == CMDTYPE_POLLING) //查询 { //这里写入自己的处理程序 } else if(cmdtype == CMDTYPE_SAVING) //保存 { //这里写入自己的处理程序 } else if(cmdtype == CMDTYPE_CHANGING) //改变 { //这里写入自己的处理程序 } else { //这里写入自己的处理程序 } return 1; } //通用的完善协议解析程序 //赋值三个字符串，地址，syntaxlevel（0，最简模式；1，带地址，2，带校验） //返回，cmd_type enum CMDTYPE ProtocolAnalysis(uint8_t * comstr, int comstrlength, uint8_t* modulestr, uint8_t* paramstr, uint8_t* valuestr, uint8_t * addr, uint8_t *syntaxlevel) { int16_t ix; //有符号数，防止负数变成正数，导致长度或定位计算错误 uint8_t colonflag = 0; //是否有冒号的标志 uint8_t modulelength = 0; uint8_t paramlength = 0; uint8_t valuelength = 0; uint8_t addrstartpos = 0; //地址字符串起始位置，@符号的下一个字符位置 uint8_t checkstartpos = 0; //校验字符串起始位置，#符号的下一个字符位置 *syntaxlevel = 0; enum CMDTYPE cmdtype = CMDTYPE_ERROR; //首先判断最后一位是否是'\r' if(comstr[comstrlength - 1] != '\r') return CMDTYPE_ERROR; else comstr[comstrlength - 1] = '\0'; //格式分析 for (ix=0; ix<comstrlength; ix++) { switch (comstr[ix]) { case ':': { modulelength = ix; colonflag = 1; break; } case '?': { paramlength = ix; cmdtype = CMDTYPE_POLLING; break; } case '^': { paramlength = ix; cmdtype = CMDTYPE_CHANGING; break; } case '=': { paramlength = ix; cmdtype = CMDTYPE_SETTING; break; } case '!': { paramlength = ix; cmdtype = CMDTYPE_SAVING; break; } case '@': { addrstartpos = ix + 1; *syntaxlevel = 1; break; } case '#': { checkstartpos = ix + 1; *syntaxlevel = 2; break; } } } if(colonflag != 1) //如果没有冒号，也是错误 { return CMDTYPE_ERROR; } if(cmdtype == CMDTYPE_ERROR) //没有正确类型，也是错误 return CMDTYPE_ERROR; if(*syntaxlevel >= 1) //有地址 { *addr = atoi(comstr + addrstartpos); //遇到#符号或者\0或者\r都会停止转换，strtol同atoi if(*syntaxlevel >= 2) //不仅有目标地址，还有校验 { //进行校验 if(CheckSum(comstr, checkstartpos) != strtol(comstr + checkstartpos, NULL, 16)) //校验不正确 return CMDTYPE_ERROR; } //获取参数字符串的长度 valuelength = addrstartpos - paramlength - 2; paramlength = paramlength - modulelength - 1; } else //无地址 { //获取参数字符串的长度 valuelength = (comstrlength - 1) - paramlength - 1; paramlength = paramlength - modulelength - 1; } //根据字符串长度来赋值，是否可以改成字符串拷贝函数 for (ix=0;ix<modulelength;ix++) { modulestr[ix] = comstr[ix]; } modulestr[ix] = '\0'; for (ix=0;ix<paramlength;ix++) { paramstr[ix] = comstr[ix+1+modulelength]; } paramstr[ix] = '\0'; if((cmdtype == CMDTYPE_CHANGING) || (cmdtype == CMDTYPE_SETTING)) { for (ix=0;ix<valuelength;ix++) { valuestr[ix] = comstr[ix + 1 + modulelength + 1 + paramlength]; } valuestr[ix] = '\0'; } return cmdtype; } uint8_t CheckSum(char * str, uint8_t length) { int i = 0; uint8_t checksum = 0; for(i=0;i<length;i++) { checksum = checksum^str[i]; } return checksum; }